The present invention relates to a built-up ingot mold for the continuous casting of metal, particularly steel.
In continuous casting, particularly of steel slabs, use is made of ingot molds comprising four cooled plates which delimit between them a cavity for the formation of a cast slab which has a specific fixed cross-section. This cavity is rectilinear in the sense of the extraction of the slab and generally has an approximately rectangular cross-section.
The plates forming two opposite walls of the cavity of the ingot mold are pressed against bearing faces formed on the other plates forming the two other opposite walls of said cavity of the ingot mold. These bearing faces simultaneously form joining faces between the plates, in the sense that they extend as far as the cavity of the ingot mold and thus define joints between the inner faces of the plates.
The plates of this ingot mold are generally tightened against one another by tightening devices acting approximately perpendicularly to the bearing faces.
The slabs cast in this type of ingot mold are then subjected to rolling in order to obtain sheets.
In point of fact, during the rolling of certain sheets, laps form at the edge of the sheet panel which, if they are too deep, persist after drawing. This defect originates from a "flow" from the upper corner of the slab to the lower corner during widening.
For example, sheets made from thick slabs of approximately 300 mm are subjected to considerable cross rolling, since a slab approximately 1700 mm wide is converted into a sheet which has a width of 4500 mm approximately. In this case, in order to avoid laps, it is essential to provide a reserve of metal, that is to say an exceptional additional width of approximately 80 mm. This additional width constitutes a major loss of material.
One solution for avoiding this lap defect consists, for example, in removing the corners of the slab by producing a bevel at each corner, using a torch.
However, the production of bevels using a torch is much too costly in terms of metal lost and preparation.
Another solution consists in directly casting slabs which are beveled at the corners by using ingot molds which comprise four cooled plates delimiting a cavity, the corners of which are cut by bevels.
Various tests performed on beveled slabs demonstrate that the bevel must have specific dimensional characteristics in order totally to avoid the defect of a lap at the edge of sheets.